A conventional coupling device preventing two drawers from being pulled out simultaneously, as shown in FIGS. 1 and 2, mainly includes a main body 10 connected to each end of a solid link 20 via a connecting element 30. The main body 10 is provided at two opposite ends with a receiving hole 101 and a horizontal recess 102, respectively. A clamping portion 103 providing a clamping slot 1031 is formed at each lateral side of the receiving hole 101; and an inward extended hook portion 104 is formed at the outer side of each clamping portion 103. Two offset guide channels 1021, 1022 are formed at front and rear side surfaces of the main body 10, respectively, to extend from the horizontal recess 102 to a middle section of the main body 10. The connecting element 30 is a substantially inverted U-shaped member having a centered through hole 301. Two inward extended middle clamping portions 302 are formed at two lateral lower sides of the through hole 301, and two sideward projections 303 with increased width and thickness are formed at two lateral ends of the connecting element 30. As can be seen from FIG. 2, the connecting element 30 is connected to the main body 10 through engagement of two arm portions at two lateral sides of the through hole 301 with the clamping slots 1031 of the clamping portions 103, and the sideward projections 303 with the hook portions 104. The solid link 20 is connected to the main body 10 and the connecting element 30 by extending an end of the link 20 through the through hole 301 on the connecting element 30 into the receiving hole 101 on the main body 10, such that the end of the link 20 is clamped between the two middle clamping portions 302. In this manner, each end of the link 20 has a main body 10 and a connecting element 30 connected thereto.
FIGS. 3 and 4 show the operation of the conventional coupling device of FIG. 2. The coupling device assembled from the main bodies 10, the connecting elements 30, and the link 20 is mounted between the rear ends of an upper and a lower sliding rail 4, 5. An upper and a lower drawer 41, 51 are slidably mounted on the upper and the lower sliding rail 4, 5, respectively, to move inward or outward. The upper and the lower drawer 41, 51 are provided at respective rear end of at least one sidewall with a guide slide 42, 52 each. The guide slides 42, 52 include a guide slot 421, 521 each, which has an open-end upper section 422, 522 and a closed-end lower section 423, 523.
A circular disk 43 having two curved guide slots 431 extended along an outer edge thereof is provided at each side of the rear end of the upper sliding rail 4, and a stopper 44 is laid between the two disks 43. Two ends of the stopper 44 are provided with a sideward protrusion 441 each, so that the sideward protrusions 441 extend into the curved guide slots 431 on the disks 43. Similarly, a circular disk 53 having two curved guide slots 531 extended along an outer edge thereof is provided at each side of the rear end of the lower sliding rail 5, and a stopper 54 is laid between the two disks 43. Two ends of the stopper 44 are provided with a sideward protrusion 541 each, so that the sideward protrusions 541 extend into the curved guide slots 531 on the disks 53.
When the lower drawer 51 mounted on the lower sliding rail 5 is pulled outward while the upper drawer 41 mounted on the upper sliding rail 4 is in a fully pushed-in position, the sideward protrusions 441 are guided by the guide slot 421 on the guide slide 42 to slide along the curved guide slots 431 to a lower location, such that the stopper 44 is in a horizontal position to fitly attach to a bottom of the horizontal recess 102 on the main body 10. Meanwhile, the sideward protrusions 541 are guided by the guide slot 521 on the guide slide 52 to slide along the curved guide slots 531 to an upper location, such that the stopper 54 is in a vertical position to press against a bottom of the horizontal recess 102 on the main body 10 at the other end of the link 20. Since the stopper 54 is pressed against the bottom of the horizontal recess 102, the main body 10 mounted on the rear end of the lower sliding rail 5 is prevented from being pushed downward. At this point, the stopper 44 is prevented from being turned, and the upper drawer 41 is in a locked state and could not be pulled out, as shown in FIG. 3. When the lower drawer 51 is pushed inward at this point, the sideward protrusions 541 are guided by the guide slot 521 on the guide slide 52 to slide along the curved guide slots 531 to a lower location, bringing the vertical stopper 54 into a horizontal position without pressing against the bottom of the horizontal recess 102 on the main body 10, so that the upper drawer 41 is released from the locked state. Reversely, when the upper drawer 41 is pulled outward, the lower drawer 51 is brought into a locked state, as shown in FIG. 4. With the above arrangements, the upper and the lower drawer 41, 51 may be effectively prevented from being pulled out simultaneously to cause any danger.
The conventional coupling device preventing two drawers from being pulled out simultaneously assembled from the main bodies 10, the link 20, and the connecting elements 30 includes a plurality of components that have different shapes and complicate structure and therefore require high R&D and management cost, which inevitably reduces the competing ability of the coupling device in the market. It is therefore tried by the inventor to develop an improved coupling device preventing two drawers from being pulled out simultaneously that has simplified structure to enable easy assembling and reduced manufacturing cost to overcome the problems existed in the conventional coupling device.